Specify shipping for specific price interval as well as weight

[hskrijelj]

I wish to make to rules/conditions regarding shipping and prices. I have tried several things so far, but with no result. The 2 rules are as following (The currency is Danish Crown - DKK):

1. When you buy products in the price interval 0-500 DKK, you have to pay additionally 50 DKK for shipping.
   
2. When you buy products for (in total) over 500 DKK, there is free shipping.
   

So far, we have managed to make the second rule (free shipping when buying for more than 500 DKK). But how can I make the first rule?

Please note that I already have some intervals regarding weight - the heavier, the more expensive.

Thanks in advance